JP2022116110A - Metal oxynitride back contact layer for photovoltaic device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a back contact capable of resolving the inoperability or instability of a photovoltaic device.

SOLUTION: A back contact for photovoltaic devices can include one or more metal oxynitride layers. The back contact 180 may be provided adjacent to an absorber layer 160. A first surface 182 of the back contact 180 may be provided upon a second surface 164 of the absorber layer 160. The back contact 180 can include binary or ternary combinations of materials from groups I, II, VI. One or more layers of the back contact can be doped with a dopant such as, for example, one or more group I dopants. Alternatively or additionally, the back contact 180 can include one or more layers containing a metal nitride material. Alternatively or additionally, the back contact 180 can include one or more layers containing a metal oxynitride material, such as, for example, titanium oxynitride, tungsten oxynitride, zirconium oxynitride, or tantalum oxynitride.

SELECTED DRAWING: Figure 1

COPYRIGHT: (C)2022,JPO&INPIT

Description

[0001] This application claims priority to US Patent Application No. 62/801,965, filed February 6, 2019, which is incorporated herein by reference.
[0002] This specification relates generally to photovoltaic devices having one or more metal back contact layers, and more particularly to photovoltaic devices having one or more metal oxynitride back contact layers. Regarding.

[0003] Photovoltaic devices generate electrical power by converting light into direct current using semiconductor materials that exhibit the photovoltaic effect. Certain semiconductor materials can be difficult to manufacture. For example, certain dopants applied to the back contact layer can diffuse through and across the back contact, leading to inoperability or instability of the photovoltaic device.

[0004] Accordingly, a need exists for alternative back contact layers for use in photovoltaic devices.

[0005] Embodiments provided herein relate to photovoltaic devices with improved back contacts. These and additional features provided by the embodiments described herein will be more fully understood in view of the detailed description below in conjunction with the drawings.

[0006] The embodiments described in the drawings are illustrative and exemplary in nature and are not intended to limit the subject matter defined by the claims. The following detailed description of the illustrative embodiments can be understood when read in conjunction with the following drawings, in which like structures are indicated by like numerals.

[0007] Figure 1 schematically illustrates a cross-sectional view of a photovoltaic device according to one or more embodiments shown and described herein; [0008] Figure 1 schematically illustrates a substrate according to one or more embodiments shown and described herein; [0009] Figure 1 schematically illustrates a cross-sectional view of a photovoltaic device according to one or more embodiments shown and described herein; [0010] Fig. 2 schematically illustrates a back contact according to one or more embodiments shown and described herein; [0010] Fig. 2 schematically illustrates a back contact according to one or more embodiments shown and described herein; [0010] Fig. 2 schematically illustrates a back contact according to one or more embodiments shown and described herein; [0010] Fig. 2 schematically illustrates a back contact according to one or more embodiments shown and described herein; [0010] Fig. 2 schematically illustrates a back contact according to one or more embodiments shown and described herein; [0011] FIG. 1 schematically illustrates a conductive layer according to one or more embodiments shown and described herein. [0012] Fig. 4 depicts a flowchart for forming a back contact according to one or more embodiments shown and described herein; [0013] Fig. 6 shows test results of a comparative example compared to a device according to one or more embodiments shown and described herein; [0014] Fig. 6 shows test results of a comparative example compared to a device according to one or more embodiments shown and described herein;

[0015] Embodiments of photovoltaic devices with metal nitride back contacts are provided herein. Various embodiments of photovoltaic devices and methods for forming photovoltaic devices are described in greater detail herein.

[0016] Referring now to Figure 1, an embodiment of a photovoltaic device 100 is schematically shown. Photovoltaic device 100 can be configured to receive and convert light into electrical signals, eg, photons can be absorbed from light and converted into electrical signals via the photovoltaic effect. Accordingly, the photovoltaic device 100 can define an energy side 102 configured to be exposed to a light source, such as the sun. The photovoltaic device 100 can also define an opposite side 104 that is offset from the energy side 102, such as by, for example, multiple layers of material. The term "light" can refer to various wavelengths of the electromagnetic spectrum, including, but not limited to, wavelengths in the ultraviolet (UV), infrared (IR), and visible portions of the electromagnetic spectrum. "Sunlight" as used herein refers to light emitted by the sun. Photovoltaic device 100 can include multiple layers disposed between energy side 102 and opposite side 104 . As used herein, the term "layer" refers to the thickness of material provided on a surface. Each layer can cover all or any portion of the surface.

[0017] Referring collectively to FIGS. 1 and 2, the layers of the photovoltaic device 100 can include a substrate 110 configured to facilitate the transmission of light into the photovoltaic device 100. . A substrate 110 may be located on the energy side 102 of the photovoltaic device 100 . The substrate 110 has a first surface 112 substantially facing the energy side 102 of the photovoltaic device 100 and a second surface 114 substantially facing the opposite side 104 of the photovoltaic device 100 . be able to. One or more layers of material may be disposed between first surface 112 and second surface 114 of substrate 110 .

[0018] The substrate 110 has a first surface 122 substantially facing the energy side 102 of the photovoltaic device 100 and a second surface 124 substantially facing the opposite side 104 of the photovoltaic device 100. may include a transparent layer 120 having a . In some embodiments, second surface 124 of transparent layer 120 can form second surface 114 of substrate 110 . Transparent layer 120 may be formed from a substantially transparent material such as glass, for example. Suitable glasses may include soda-lime glass, or any glass having reduced iron content. Transparent layer 120 may have any suitable transmittance, including from about 250 nm to about 1,300 nm in some embodiments, or from about 250 nm to about 950 nm in other embodiments. The transparent layer 120 is, for example, greater than about 50% in one embodiment, greater than about 60% in another embodiment, greater than about 70% in yet another embodiment, greater than about 80% in a further embodiment, or in another embodiment Further embodiments may have any suitable transmission, including greater than about 85%. In one embodiment, transparent layer 120 may be formed from glass having a transmittance of about 90% or greater. Optionally, substrate 110 can include coating 126 applied to first surface 122 of transparent layer 120 . Coating 126 may be configured to interact with light or to improve the durability of substrate 110 including, but not limited to, antireflective coatings, antifouling coatings, or combinations thereof.

[0019] Referring again to FIG. 1, the photovoltaic device 100 includes a barrier layer configured to mitigate diffusion of contaminants (eg, sodium) from the substrate 110 that can lead to degradation or delamination. 130 can be included. The barrier layer 130 has a first surface 132 substantially facing the energy side 102 of the photovoltaic device 100 and a second surface 134 substantially facing the opposite side 104 of the photovoltaic device 100 . can have In some embodiments, barrier layer 130 may be provided adjacent to substrate 110 . For example, first surface 132 of barrier layer 130 may be provided on second surface 114 of substrate 100 . The phrase “adjacent to,” as used herein, means that two layers are placed in contact without any intervening material between at least a portion of the layers.

[0020] In general, the barrier layer 130 can be substantially transparent, thermally stable, have a low number of pinholes, have a high sodium blocking capability, and have good adhesion. Alternatively or additionally, barrier layer 130 may be configured to apply color suppression to light. Barrier layer 130 may comprise one or more layers of suitable materials including, but not limited to, tin oxide, silicon dioxide, aluminum doped silicon oxide, silicon oxide, silicon nitride, or aluminum oxide. . Barrier layer 130 may have any suitable thickness (e.g., greater than about 100 Å in one embodiment, greater than about 150 Å in another embodiment, or even greater than about 150 Å in another embodiment) as limited by first surface 132 and second surface 134 . (including less than about 200 Å in embodiments).

[0021] Still referring to FIG. 1, the photovoltaic device 100 includes a transparent conductive oxide (TCO) material configured to provide electrical contacts and transport charge carriers generated by the photovoltaic device 100. A layer 140 may be included. The TCO layer 140 has a first surface 142 substantially facing the energy side 102 of the photovoltaic device 100 and a second surface 144 substantially facing the opposite side 104 of the photovoltaic device 100 . can have In some embodiments, TCO layer 140 may be provided adjacent to barrier layer 130 . For example, first surface 142 of TCO layer 140 may be provided on second surface 134 of barrier layer 130 . In general, TCO layer 140 may be formed from one or more layers of a substantially transparent, wide bandgap n-type semiconductor material. Specifically, a wide bandgap can have a large energy value compared to the energy of a photon of light, and can mitigate unwanted light absorption. The TCO layer 140 may be made of any suitable material including, but not limited to, tin oxide, fluorine _- doped tin oxide (e.g., F:SnO, F:SnO2 or F: _SnOx ), indium tin oxide, or cadmium stannate. It can include one or more layers of material.

[0022] The photovoltaic device 100 can include a buffer layer 150 that is configured to provide an insulating layer between the TCO layer 140 and any adjacent semiconductor layers. The buffer layer 150 has a first surface 152 substantially facing the energy side 102 of the photovoltaic device 100 and a second surface 154 substantially facing the opposite side 104 of the photovoltaic device 100 . can have In some embodiments, buffer layer 150 may be provided adjacent to TCO layer 140 . For example, first surface 152 of buffer layer 150 may be provided on second surface 144 of TCO layer 140 . The buffer layer 140 is made of a material having a higher resistivity than the TCO layer 140, including but not limited to intrinsic tin oxide (SnO, SnO ₂ or SnO _x ), magnesium oxide (MgO), zinc magnesium oxide (eg, Zn _{1- x} Mg _x O), silicon dioxide (SiO ₂ ), manganese oxide (MnO _x ), silicon nitride (SiN _x ), or any combination thereof).

[0023] The photovoltaic device 100 can include an absorber layer 160 that is configured to cooperate with another layer to form a pn junction within the photovoltaic device 100. As shown in FIG. Correspondingly, absorbed photons of light can release electron-hole pairs and generate carrier flow, producing electrical power. The absorbing layer 160 has a first surface 162 substantially facing the energy side 102 of the photovoltaic device 100 and a second surface 164 substantially facing the opposite side 104 of the photovoltaic device 100 . can have A thickness of absorbent layer 160 may be defined between first surface 162 and second surface 164 . Absorbent layer 160 may have a thickness from about 0.5 μm to about 10 μm, such as from about 1 μm to about 7 μm in one embodiment, or from about 1.5 μm to about 4 μm in another embodiment.

[0024] According to embodiments described herein, absorber layer 160 may be formed from a p-type semiconductor material having an excess of positive charge carriers, ie, holes or acceptors. Absorbing layer 160 may comprise any suitable p-type semiconductor material, such as a II-VI semiconductor. Examples include, but are not limited to, semiconductor materials comprising cadmium, tellurium, selenium, or any combination thereof. Suitable examples include, but are not limited to, ternaries of cadmium, selenium and tellurium (eg, CdSe _x Te _1-x ), or compounds containing cadmium, selenium, tellurium, and one or more additional elements. mentioned.

[0025] In embodiments in which absorber layer 160 comprises tellurium and cadmium, the atomic percentage of tellurium is greater than or equal to about 25 atomic percent and less than or equal to about 50 atomic percent, such as greater than about 30 atomic percent and about 50 atomic percent in one embodiment. less than, in further embodiments, greater than about 40 atomic percent, less than about 50 atomic percent, or in yet other embodiments greater than about 47 atomic percent, less than about 50 atomic percent, and the like. Alternatively or additionally, the atomic percentage of tellurium in absorber layer 160 may be greater than about 45 atomic percent, such as greater than about 49% in one embodiment. The atomic percentages described herein refer to the entire absorber layer 160, and the atomic percentage of material at a particular location within the absorber layer 160 varies with thickness relative to the overall composition of the absorber layer 160. Note that we get

[0026] In embodiments where the absorber layer 160 comprises selenium and tellurium, the atomic percentage of selenium in the absorber layer 160 is greater than about 0 atomic percent and less than or equal to about 25 atomic percent, such as greater than about 1 atomic percent in one embodiment. , less than about 20 atomic percent, in other embodiments greater than about 1 atomic percent and less than about 15 atomic percent, or in further embodiments greater than about 1 atomic percent and less than about 8 atomic percent. Note that the concentration of tellurium, selenium, or both can vary through the thickness of absorber layer 160 . For example, when absorber layer 160 includes a compound (Se _x Te _1-x ) containing a mole fraction of x selenium and a mole fraction of tellurium of 1-x, x is in absorber layer 160 and absorber layer 160 may vary depending on the distance from the first surface 162 of the .

[0027] Still referring to Figure 1, the absorbing layer 160 can be doped with a dopant configured to manipulate the concentration of charge carriers. In some embodiments, absorbing layer 160 may be doped with dopants such as, for example, one or more Group I dopants, one or more Group V dopants, or combinations thereof. The total density of dopants in absorber layer 160 can be controlled. Alternatively or additionally, the amount of dopant may vary depending on the distance of the absorbing layer 160 from the first surface 162 .

[0028] According to embodiments provided herein, a pn junction is formed by providing the absorber layer 160 sufficiently close to the portion of the photovoltaic device 100 that has excess negative charge carriers, ie electrons or donors. be able to. In some embodiments, absorber layer 160 may be provided adjacent to the n-type semiconductor material. Alternatively, one or more intervening layers may be provided between the absorbing layer 160 and the n-type semiconductor material. In some embodiments, absorbent layer 160 may be provided adjacent to buffer layer 150 . For example, first surface 162 of absorbent layer 160 may be provided on second surface 154 of buffer layer 150 .

[0029] Referring now to Figure 3, in some embodiments, a photovoltaic device 200 can include a window layer 170 comprising an n-type semiconductor material. Apart from window layer 170, photovoltaic device 200 may have a layer structure substantially similar to photovoltaic device 100 (FIG. 1). Absorbing layer 160 may be formed adjacent to window layer 170 . The window layer 170 has a first surface 172 substantially facing the energy side 102 of the photovoltaic device 200 and a second surface 174 substantially facing the opposite side 104 of the photovoltaic device 200 . can have In some embodiments, window layer 170 may be located between absorber layer 160 and TCO layer 140 . In one embodiment, window layer 170 may be located between absorbent layer 160 and buffer layer 150 . Window layer 170 may comprise any suitable material including, for example, cadmium sulfide, zinc sulfide, cadmium zinc sulfide, zinc magnesium oxide, or any combination thereof.

[0030] Referring again to FIGS. 1 and 3, the photovoltaic device 100, 200 includes a back contact 180 configured to mitigate unwanted changes in dopant and provide electrical contact to the absorber layer 160. can contain. The back contact 180 has a first surface 182 substantially facing the energy side 102 of the photovoltaic device 100 and a second surface 184 substantially facing the opposite side 104 of the photovoltaic device 100 . can have A thickness of back contact 180 may be defined between first surface 182 and second surface 184 . The thickness of the back contact 180 may be from about 5 nm to about 220 nm, such as from about 10 nm to about 200 nm in one embodiment, or from about 10 nm to about 150 nm in one embodiment. The multiple layers between (including both) the substrate 110 and the absorber layer 160 may be referred to as an absorber stack 109,209. A back contact 180 may be positioned above the absorber stack 109,209.

[0031] In some embodiments, a back contact 180 may be provided adjacent to the absorbing layer 160. As shown in FIG. For example, first surface 182 of back contact 180 may overlie second surface 164 of absorbing layer 160 . In some embodiments, the back contact 180 can comprise a binary or ternary combination of materials from Groups I, II, and VI. For example, back contact 180 can include one or more layers containing zinc, cadmium, tellurium, or combinations thereof. In some embodiments, one or more layers of the back contact may be doped with dopants such as, for example, one or more Group I dopants. Alternatively or additionally, the back contact 180 may be a metal nitride material, such as MoN _x (with an N composition where x is in the range 0<x<1), TiN _y (with y in the range 0<y<1.1). ), WN _z (with an N composition in the range 0<z<1.1), TaN _i (with an N composition in the range 0<i<1.1) ), or ZrN _j (with an N composition in the range 0<j<1.1, where j). Generally, the metal nitride material is substantially free of oxidation, i.e., the metal nitride material contains less than about 1% oxygen (atomic %), such as less than about 0.5% oxygen. . Alternatively or additionally, back contact 180 includes one or more layers containing a metal oxynitride material, such as titanium oxynitride, tungsten oxynitride, zirconium oxynitride, or tantalum oxynitride. be able to. In some embodiments, the titanium oxynitride is TiO _a N _b (O composition where a is 0<a<1.0 and N ₂ composition where b is 0<b<1.1 ) can be defined as In some embodiments, the tungsten oxynitride is WO _c N _d (O composition with c in the range 0<c<1.0 and _N2 composition with d in the range 0<d<1.1 ) can be defined as

[0032] Referring collectively to FIGS. Multiple layers 202 of back contact 180 may include a layer 210 comprising a metal oxynitride material. In some embodiments, layer 210 may consist of a metal oxynitride material. In some embodiments, at least a portion of the metal oxynitride material may be composed of a Group IV, Group V, or Group VI transition metal such as, for example, titanium or tungsten. The metal oxynitride material may be composed of less than about 70% transition metal (atomic %), for example, in one embodiment about 25% to about 60% metal oxynitride material is the transition metal. There may be, or in another embodiment about 30% to about 50% of the metal oxynitride material may be the transition metal. The metal oxynitride material may be composed of less than about 50% oxygen (atomic %), for example, even though in one embodiment about 5% to about 40% of the metal oxynitride material is oxygen. Well, or in another embodiment about 10% to about 25% of the metal oxynitride material may be oxygen. The metal oxynitride material may be composed of less than about 50% nitrogen (atomic %), for example even though in one embodiment about 10% to about 45% of the metal oxynitride material is nitrogen. Well, or in another embodiment about 25% to about 40% of the metal oxynitride material may be nitrogen.

[0033] The layer 210 has a first surface 212 substantially facing the energy side 102 of the photovoltaic device 100,200 and a second surface 212 substantially facing the opposite side 104 of the photovoltaic device 100,200. and a surface 214 of . In some embodiments, second surface 214 of layer 210 may be second surface 184 of back contact 180 . A thickness of layer 210 may be defined between first surface 212 and second surface 214 . The thickness of the layer 210 comprising the metal oxynitride material is from about 1 nm to about 20 nm, such as from about 2 nm to about 20 nm in one embodiment, from about 3 nm to about 20 nm in another embodiment, and from about 1 nm in a further embodiment. to about 5 nm, or in further embodiments from about 5 nm to about 10 nm, and the like.

[0034] The plurality of layers 202 of the back contact 180 includes one containing zinc, cadmium, tellurium, or a combination between the layer 210 including the metal oxynitride material and the first surface 182 of the back contact 180. or may include multiple layers. For example, the plurality of layers 202 of the back contact 180 includes one or more layers containing zinc and tellurium between the layer 210 including the metal oxynitride material and the first surface 182 of the back contact 180. can be done. In some embodiments, the plurality of layers 202 of the back contact 180 includes a first layer 220 and a first layer 220 disposed between the layer 210 including the metal oxynitride material and the first surface 182 of the back contact 180 . 2 layers 230 can be included. First layer 220 of back contact 180 may be disposed on first surface 182 of back contact 180 . Accordingly, the first layer 220 may be provided adjacent to the absorbent layer 160 . In some embodiments, first surface 182 of back contact 180 may be first surface 222 of first layer 220 . First layer 220 may have a second surface 224 substantially facing opposite side 104 of photovoltaic device 100 . The first layer 220 of the back contact 180 may include the ternary cadmium, zinc, and tellurium. In some embodiments, the first layer 220 may consist of the ternary cadmium, zinc, and tellurium.

A second layer 230 may be disposed between the layer 210 comprising the metal oxynitride material and the first layer 220 of the back contact 180 . A thickness of second layer 230 may be defined between first surface 232 and second surface 234 . In some embodiments, the second layer 230 may be provided adjacent to the first layer 220 and the layer 210 comprising the metal oxynitride material. Accordingly, the first surface 232 of the second layer 230 may contact the second surface 224 of the first layer 220 and the second surface 234 of the second layer 230 may be the layer 210 may be in contact with first surface 212 . The first layer 230 of the back contact 180 may comprise zinc and tellurium binary, which may be doped with dopants (eg, copper, silver, or both). In some embodiments, the second layer 230 may consist of a doped binary of zinc and tellurium.

[0036] Referring collectively to FIGS. The plurality of layers 204 of the back contact 180 can include a high purity metal layer 240 that includes a high concentration (atomic %) of a group IV transition metal, a group V transition metal, or a group VI transition metal, e.g., about 80% The ultra-pure metal layer 240 may be composed of the selected transition metal in one embodiment, or in one embodiment the greater than about 90% high-purity metal layer 240 is composed of the selected transition metal. may have been In some embodiments, high purity metal layer 240 can include a high concentration of titanium. In one example, the high purity metal layer consists essentially of titanium. In one example, the high purity metal layer consists essentially of titanium, tungsten, tantalum, zirconium, or combinations thereof.

[0037] The high purity metal layer 240 has a first surface 242 substantially facing the energy side 102 of the photovoltaic device 100, 200 and a substantially opposite side 104 of the photovoltaic device 100, 200. and a second surface 242 . A thickness of high purity metal layer 240 may be defined between first surface 242 and second surface 244 . The thickness of the high purity metal layer 240 may be from about 1 nm to about 5 nm. Alternatively or additionally, the thickness of the high purity metal layer 240 may be less than the thickness of the layer 210 comprising the metal oxynitride material. In some embodiments, the ratio of the thickness of layer 210 comprising metal oxynitride material to the thickness of high purity metal layer 240 can be at least about 2:1.

[0038] The high purity metal layer 240 may be located closer to the first surface 182 of the back contact 180 than the layer 210 comprising the metal oxynitride material. In some embodiments, high purity metal layer 240 may be disposed between layer 210 comprising metal oxynitride material and one or more layers containing zinc and tellurium. For example, high purity metal layer 240 may be adjacent to layer 210 comprising a metal oxynitride material. Accordingly, the second surface 244 of the high purity metal layer 240 may contact the first surface 212 of the layer 210 comprising the metal oxynitride material. Alternatively or additionally, the high purity metal layer 240 may be adjacent to the second layer 230 of the back contact 180, i. 2 may contact surface 234 .

[0039] Referring collectively to FIGS. The plurality of layers 206 of the back contact 180 comprises a metal nitride material having a metal concentration (atomic %) of about 30% to about 70% and a nitrogen concentration (atomic %) of about 70% to about 30%. A containing layer 250 can be included. Suitable metals include, but are not limited to molybdenum, titanium, and tungsten. In some embodiments, layer 250 may consist of a metal nitride. A layer 250 comprising a metal nitride has a first surface 252 substantially facing the energy side 102 of the photovoltaic device 100, 200 and substantially facing the opposite side 104 of the photovoltaic device 100, 200. a second surface 254; A thickness of layer 250 comprising metal nitride may be defined between first surface 252 and second surface 254 . The thickness of layer 250 comprising metal nitride may be from about 2 nm to about 20 nm. Alternatively or additionally, the thickness of layer 250 comprising metal nitride may be greater than the thickness of layer 210 comprising metal oxynitride material. In some embodiments, the ratio of the thickness of layer 250 comprising metal nitride to the thickness of layer 210 comprising metal oxynitride material is at least about 2:1, for example at least about It can be 3:1, and so on.

[0040] A layer 250 comprising a metal nitride may be located closer to the second surface 184 of the back contact 180 than a layer 210 comprising a metal oxynitride material. In some embodiments, layer 250 comprising metal nitride may be adjacent to layer 210 comprising metal oxynitride material. Accordingly, second surface 214 of layer 210 comprising metal oxynitride material may contact first surface 252 of layer 250 comprising metal nitride. Alternatively or additionally, second surface 254 of layer 250 comprising metal nitride may be second surface 184 of back contact 180 .

[0041] Referring collectively to FIGS. Multiple layers 208 of back contact 180 may include a second layer 260 comprising a metal oxynitride material. The second layer 260 comprising metal oxynitride material may be substantially similar to layer 210 comprising metal oxynitride material. In some embodiments, layer 210 including metal oxynitride material and second layer 260 including metal oxynitride material can be formed from different metals. In some embodiments, layer 210 can include _TiOaNb and second layer ₂₆₀ can include _{WOcNd .} Alternatively, layer ₂₁₀ can comprise _WOcNd and second layer ₂₆₀ can comprise _TiOaNb .

[0042] The second layer 260 comprising a metal oxynitride material may be located closer to the first surface 182 of the back contact 180 than the layer 210 comprising a metal oxynitride material. A second layer 260 comprising a metal oxynitride material is disposed on a first surface 262 substantially facing the energy side 102 of the photovoltaic device 100,200 and on the opposite side 104 of the photovoltaic device 100,200. and a substantially facing second surface 264 . In some embodiments, layer 260 comprising metal oxynitride may be adjacent to layer 210 comprising metal oxynitride material. Accordingly, second surface 264 of second layer 260 comprising metal oxynitride material may contact layer 210 comprising metal oxynitride material. Alternatively or additionally, a second layer 260 comprising metal oxynitride material may be located between layer 210 comprising metal oxynitride material and one or more layers containing zinc and tellurium. . In some embodiments, the second layer 260 comprising metal oxynitride material may be adjacent to one or more layers containing zinc and tellurium. For example, first surface 262 of second layer 260 may contact second surface 234 of second layer 230 of back contact 180 .

[0043] Referring collectively to FIGS. Multiple layers 209 of back contact 180 may include a second layer 270 comprising a metal nitride material. A second layer 270 comprising a metal nitride material is formed on a first surface 272 substantially facing the energy side 102 of the photovoltaic device 100,200 and substantially on the opposite side 104 of the photovoltaic device 100,200. and a second surface 274 facing the surface. The second layer 270 comprising metal nitride material may be substantially similar to layer 250 comprising metal nitride material. In some embodiments, layer 250 including metal nitride material and second layer 270 including metal nitride material can be formed from different metals. Alternatively, the layer 250 comprising a metal nitride material and the second layer 270 comprising a metal nitride material can be formed from the same material.

[0044] The second layer 270 comprising a metal nitride material may be located closer to the first surface 182 of the back contact 180 than the layer 210 comprising a metal oxynitride material. In some embodiments, a second layer 270 comprising a metal nitride may be adjacent to a layer 210 comprising a metal oxynitride material. Accordingly, second surface 274 of second layer 270 comprising metal oxynitride material may contact first surface 212 of layer 210 comprising metal oxynitride material. Alternatively or additionally, a second layer 270 comprising a metal nitride material may be located between the layer 210 comprising a metal oxynitride material and one or more layers containing zinc and tellurium. . In some embodiments, a second layer 270 comprising a metal nitride material may be adjacent to one or more layers containing zinc and tellurium. For example, first surface 272 of second layer 270 may contact second surface 234 of second layer 230 of back contact 180 .

[0045] With collective reference to FIGS. . The conductive layer 190 has a first surface 192 substantially facing the energy side 102 of the photovoltaic device 100 and a second surface 194 substantially facing the opposite side 104 of the photovoltaic device 100 . can have In some embodiments, conductive layer 190 may be provided adjacent back contact 180 . For example, first surface 192 of conductive layer 190 may be provided on second surface 184 of back contact 180 . Conductive layer 190 can also include any suitable conductive material such as, for example, one or more layers of silver, nickel, copper, aluminum, titanium, palladium, chromium, molybdenum, gold, or alloys thereof. can. In some embodiments, the first surface 192 of the conductive layer 190 is a layer 276 comprising aluminum, such as a layer comprising at least about 90% aluminum (atomic %) (eg, at least about 95% aluminum). can be formed by Alternatively or additionally, second surface 194 of conductive layer 190 may be formed by layer 278 comprising chromium.

[0046] The photovoltaic device 100 can include a back support 196 configured to cooperate with the substrate 110 to form a housing for the photovoltaic device 100. As shown in FIG. A back support 196 may be located on the opposite side 102 of the photovoltaic device 100 . For example, back support 196 may be formed over conductive layer 190 . The back support 196 can comprise any suitable material including, for example, glass (eg, soda-lime glass).

[0047] The layers of the photovoltaic devices 100, 200 and devices described herein may be formed by a manufacturing process. Layers may be formed by, but not limited to, sputtering, vapor transport deposition (VTD), pulsed laser deposition (PLD), chemical vapor deposition (CVD), electrochemical deposition (ECD), vapor deposition, and/or atomic layer deposition. It may be formed by one or more vapor deposition processes, including deposition methods (ALD).

[0048] A method of manufacturing a photovoltaic structure may include sequentially forming layers on a substrate. The TCO layer may be formed on a substrate layer such as glass. Optionally, a buffer layer, window layer, and/or interfacial layer may be deposited over the substrate (including over the previously applied TCO layer). The absorber layer can be deposited over the substrate, including any interfacial layer, any n-type window layer, any buffer layer, the TCO layer, and the substrate. A plurality of layers between the substrate and the absorber layer (including the substrate and the absorber layer) may be referred to as an absorber stack. The absorber stack may be treated, for example by heating, activation and/or passivation, prior to applying the back contact layer. One or more layers are deposited to form a conductive layer over the back contact layer. A back support may be formed over the conductive layer. Scribe lines may be formed through selected layers during the manufacturing process.

[0049] Precursor layers and processes can be applied to introduce dopants and/or to achieve specific final layer compositions and structures. Layer deposition may include deposition of one or more precursor layers that require annealing or heating steps after deposition to form the layers. By way of example, in embodiments where the absorber layer is formed from one or more precursor layers, a first precursor layer, such as cadmium selenide (CdSe), is deposited over the substrate structure followed by A second precursor layer, for example cadmium telluride (CdTe), is deposited over the first precursor layer. The deposited precursor layers are then annealed to form the desired final layer composition, for example, a cadmium-selenium-tellurium alloy (CdSeTe). The annealing step causes interdiffusion of Se through the CdSeTe layer.

[0050] An activation process may be performed on the deposited layer. As an example, an absorber activation step can be used to form an activated p-type absorber layer. _The absorber activation step involves the introduction of a chlorine containing material into the semiconductor material layer, e.g. and annealing. For example, if _CdCl2 is used, the _CdCl2 can be applied as an aqueous solution on top of the absorbing layer. Alternatively, the absorber layer can be annealed with _CdCl2 by continuously flowing _CdCl2 vapor over the surface of the absorber layer during the annealing step. Alternative chlorine doping materials such as _MnCl2 , _MgCl2 , _NH4Cl , _ZnCl2 , or _TeCl4 can also be used. Exemplary annealing can be performed at a temperature of about 350° C. to 475° C. for a total duration of 90 minutes or less with an immersion time of 60 minutes or less.

[0051] A multi-step activation process may be used. Desired layer properties using different thermal activation energies with each desired activation mechanism during a multi-step activation process such as semiconductor grain growth, chlorine diffusion, interdiffusion of sulfur and/or selenium into the layer can be realized.

[0052] In one example, the absorber activation step is followed by cleaning and passivation steps followed by sequential deposition of multiple layers forming the back contact.
[0053] Turning now to FIG. 10 with reference to FIGS. 4-8, an example method 900 for forming the back contact 180 is shown. An absorbent stack is provided (901). Optionally, the absorber stack can be passivated (902). A plurality of layers (202, 204, 206, 208) forming the back contact 180 are deposited. In the example method for forming the back contact, a first layer 220 is deposited 220 over the absorber stack 109,209. A second layer 230 is deposited over the first layer 220 . Optionally, one or more selected layers 240, 260, 270 are deposited (940, 960, 970) over the second layer. The selected layers may include one or more of a high purity metal layer, a second metal oxynitride layer, or a second metal nitride layer. Materials are deposited 910 to form a layer 210 comprising a first metal oxynitride. Layer 250 , which may optionally include a metal nitride, is deposited over layer 210 . Second surface 184 of back contact 180 may be second surface 254 of layer 250 if optional layer 250 is present, or second surface 254 of layer 210 including metal oxynitride if layer 250 and step 950 are omitted. 2 surface 214. Optionally, the layer stack including multiple layers containing the back contact may be heat treated. Scribing may be performed. One or more layers of conductive material are deposited 990 on the second surface 184 of the back contact 180 to form a conductive layer 190 .

[0054] Figures 11-12 show test results of an example device compared to a comparative example. In the example process, a DC magnetron reactive sputtering process was used to form the metal nitride layer. The process pressure varied from 2-15 mTorr, the temperature ranged from room temperature to about 200° C., the N ₂ % ranged from about 14-70%, the process flow rate varied from 200-1000 sccm for N ₂ and the gas mixture is mainly Ar+N ₂ (metal nitride) or Ar+O ₂ +N ₂ (metal oxynitride). The Al and Cr conductive layers are deposited using DC magnetron sputtering using Ar only.

[0055] Figure 11 shows increasing efficiency along the y-axis and shows eleven columns along the x-axis, each column corresponding to a set of devices. The two columns on the left are comparative examples. Two sets of comparative examples: Comparative Example A and Comparative Example B are shown. A comparative example has a back contact comprising a ZnTe:Cu/MoN _x back contact. The right nine columns of comparative examples show a set of devices according to embodiments of the present invention, comparing metal nitride layer thickness and nitrogen content between different columns. In these device examples, no MoN _x layer is present. Example devices were prepared using titanium nitride layers with thicknesses of 40, 60, 70 or 80 Angstroms (4.0, 6.0, 7.0 or 8.0 nm). A comparative example included a MoN _x layer with a thickness of 50 Angstroms (5.0 nm) and no TiN _x layer. Example devices were prepared with points selected in the range of N ₂ % from 33% to 50%. Comparative examples were prepared within the N ₂ % range of 33% to 50%. Device examples and comparative examples were prepared under similar deposition conditions, including temperature and pressure conditions.

[0056] Figure 12 shows increasing efficiency along the y-axis and grouping of devices along the x-axis. Comparative examples are the middle and left sets, and device examples are shown in the right group. As shown, the example device demonstrated higher efficiency than the comparative example.

[0057] In an embodiment of the invention, the back contact comprises multiple layers. In one example, the plurality of layers are CdZnTe layers comprising alloys of cadmium, tellurium, and zinc, and optionally including dopants such as copper and/or silver, disposed adjacent to the absorber stack. a ZnTe layer disposed adjacent to the CdZnTe layer and comprising zinc telluride doped with copper and/or silver; titanium (Ti), tungsten (W), tantalum (Ta), or zirconium (Zr) a metal oxynitride layer containing at least one transition metal selected from the group consisting of a metal oxynitride layer disposed adjacent to a ZnTe layer; and titanium (Ti), tungsten (W), A metal nitride layer disposed adjacent to the metal oxynitride layer containing at least one transition metal selected from the group consisting of tantalum (Ta) or zirconium (Zr). A conductive layer may be disposed over the back contact and adjacent to the metal nitride layer. In the device example, the metal nitride includes titanium nitride and the oxynitride includes titanium oxynitride.

[0058] In embodiments of the present invention, the back contact includes multiple layers. In one example, the plurality of layers comprises an alloy of cadmium, tellurium, and zinc, optionally doped with copper and/or silver, a CdZnTe layer positioned adjacent to the absorber stack; A ZnTe layer containing zinc telluride, optionally doped with copper and/or silver, placed adjacently; consisting of titanium (Ti), tungsten (W), tantalum (Ta), or zirconium (Zr). A high-purity metal layer comprising at least one transition metal selected from the group, the high-purity metal layer being positioned adjacent to the ZnTe layer; a backside comprising a metal oxynitride layer and/or a metal nitride layer A high-purity metal layer comprising at least one transition metal selected from the group consisting of titanium (Ti), tungsten (W), tantalum (Ta), zirconium (Zr), or molybdenum (Mo) a backing layer positioned adjacent to the backing layer; and a conductive layer positioned adjacent to the backing layer. In the example device, the high purity metal layer comprises titanium and the back layer comprises molybdenum and/or titanium.

[0059] In an embodiment of the invention, the back contact comprises multiple layers. In one example, the plurality of layers is at least one surface layer comprising an alloy of tellurium and zinc, optionally alloyed with cadmium and optionally doped with copper and/or silver, wherein the absorbing at least one surface layer disposed adjacent to the body stack; comprising at least one transition metal selected from the group consisting of titanium (Ti), tungsten (W), tantalum (Ta), or zirconium (Zr); A high purity metal layer disposed on at least one surface layer; a back layer comprising a metal oxynitride layer and/or a metal nitride layer comprising titanium (Ti), tungsten (W), tantalum (Ta), zirconium (Zr), or molybdenum (Mo), comprising at least one transition metal selected from the group consisting of molybdenum (Mo); It includes a conductive layer positioned adjacent to the layer. In the example device, the high purity metal layer comprises titanium and the back layer comprises molybdenum and/or titanium.

[0060] In an embodiment of the invention, the back contact comprises multiple layers. In one example, the plurality of layers comprises an alloy of cadmium, tellurium, and zinc, optionally doped with copper and/or silver, a CdZnTe layer disposed over the absorber stack; Disposed ZnTe layer comprising zinc telluride, optionally doped with copper and/or silver; titanium (Ti), tungsten (W), tantalum (Ta), zirconium (Zr), and/or chromium A metal oxynitride layer containing at least one transition metal selected from the group consisting of (Cr), the metal oxynitride layer disposed on a ZnTe layer; titanium (Ti), tungsten (W) , tantalum (Ta), zirconium (Zr), and/or chromium (Cr), wherein the metal nitride is disposed adjacent to the metal oxynitride layer. Layer; metal oxynitride layer containing at least one transition metal selected from the group consisting of titanium (Ti), tungsten (W), tantalum (Ta), zirconium (Zr), and/or molybdenum (Mo) and a second metal nitride layer disposed between and adjacent to the ZnTe layer. A conductive layer may be disposed over the metal nitride layer of the back contact. In one example, the conductive layer may include multiple layers including aluminum and chromium. In the example device, the metal nitride comprises titanium nitride, the second metal nitride comprises titanium nitride, and the oxynitride comprises titanium oxynitride.

[0061] In an embodiment of the invention, the back contact comprises multiple layers. In one example, the plurality of layers includes at least one front layer comprising an alloy of tellurium and zinc, optionally alloyed with cadmium and optionally doped with copper and/or silver, wherein cadmium at least one front layer disposed over an absorber stack comprising an absorber layer having , tellurium, and selenium; ), tungsten (W), tantalum (Ta), or zirconium (Zr). A conductive layer may be disposed on the back surface layer of the back contact. In example devices, the backside layer includes titanium nitride and/or titanium oxynitride, and the device does not include molybdenum.

[0062] In an example method, at least one layer of the back contact is deposited by vapor transport deposition (VTD) onto a substrate stack conveyed along a deposition path. The precursor material is heated to form a vapor that is directed to the substrate by the carrier gas.

[0063] In an example method, the back contact is formed by a VTD process and sputtering. In one embodiment, the cadmium, tellurium, and zinc alloy is deposited by VTD and the nitride and/or oxynitride layers are deposited by reactive magnetron sputtering.

[0064] In some examples, the metal of the metal nitride material includes molybdenum, titanium, tungsten, tantalum, and/or zirconium.
[0065] In some examples, the metal of the metal nitride material includes at least one of titanium, tungsten, tantalum, or zirconium.

[0066] In an embodiment of the invention, the absorber stack includes a p-type absorber layer comprising cadmium and tellurium.
[0067] In one example, the absorber stack includes a p-type absorber layer comprising cadmium, tellurium, and selenium.

[0068] In some examples, the back contact is between and adjacent to the absorber stack and the conductive layer.
[0069] In some examples, the conductive layer includes at least one layer comprising aluminum adjacent to at least one layer comprising chromium.

[0070] In some examples, the metal oxynitride material comprises 30% to 70% Group IV transition metal, Group V transition metal, or Group VI transition metal, and the metal oxynitride material comprises 1% to 15% of oxygen.
[0071] In one example, the metal oxynitride material comprises 30% to 50% nitrogen, 2% to 8% oxygen, and 42% to 68% titanium (Ti), tungsten (W), tantalum ( Ta) and at least one metal selected from the group consisting of zirconium (Zr).

[0072] In some examples, the photovoltaic device does not include molybdenum (Mo).
[0073] In one example, the metal oxynitride layer consists essentially of titanium oxynitride. In some embodiments, the layer containing titanium oxynitride material contains less than 25% oxygen. In some embodiments, the layer comprising titanium oxynitride material comprises 2% to 15% oxygen. In some embodiments, the layer comprising titanium oxynitride material has a thickness in the range of 0.5 nm to 5.0 nm.

[0074] In some examples, the metal oxynitride layer consists essentially of tungsten oxynitride. In some embodiments, the layer comprising tungsten oxynitride material comprises less than 25% oxygen. In some embodiments, the layer comprising tungsten oxynitride material comprises 1% to 20% oxygen. In some embodiments, the layer comprising tungsten oxynitride material has a thickness in the range of 0.5 nm to 5.0 nm.

[0075] In some examples, the metal oxynitride layer consists essentially of tantalum oxynitride.
[0076] In some examples, the metal oxynitride layer consists essentially of zirconium oxynitride.
[0077] In one example, the back contact comprises a first metal oxynitride layer adjacent to a second metal oxynitride layer, the first metal oxynitride layer comprising tungsten, the second metal The oxynitride layer contains titanium.

[0078] In some examples, the metal oxynitride layer comprises 1% to 50% oxygen.
[0079] In some examples, the metal oxynitride material comprises less than 50% nitrogen.
[0080] In some examples, the back contact comprises a high purity metal layer. In some embodiments, the high purity metal layer has a thickness of 1 nm to 5 nm. In some embodiments, the high purity metal layer comprises 85% to 100% or 95% to 100% composition of a single metallic element. In some embodiments, the high purity metal layer comprises a composition of 85% to 100% or 95% to 100% alloy of metal elements. In some embodiments, the high purity metal layer consists essentially of titanium.

[0081] In one example, the layer comprising the metal oxynitride material has a thickness between 1 nm and 20 nm, and the back contact has a thickness between 5 nm and 220 nm.
[0082] In another aspect, a photovoltaic device comprises an absorber stack; a conductive layer having a surface formed by a layer comprising aluminum; a back contact having a thickness defined between the surface and a second surface of the back contact, the first surface of the back contact being adjacent to the p-type absorber layer of the absorber stack; the surface of 2 contacts the surface of the conductive layer; the back contact comprises a layer comprising a metal oxynitride material and zinc positioned between the layer comprising the metal oxynitride material and the first surface of the back contact; and one or more layers containing cadmium, tellurium, or any combination thereof.

[0083] In some embodiments, the metal oxynitride material comprises a Group IV transition metal, a Group V transition metal, or a Group VI transition metal.
[0084] In some embodiments, the metal nitride material and/or metal oxynitride material comprises a group IV transition metal, a group V transition metal, or a group VI transition metal, excluding molybdenum.

[0085] In some embodiments, the metal oxynitride material comprises less than about 70% Group IV transition metal, Group V transition metal, or Group VI transition metal.
[0086] In some embodiments, the metal oxynitride material is titanium oxynitride.

[0087] In some embodiments, the metal oxynitride material is tungsten oxynitride.
[0088] In some embodiments, the metal oxynitride material is tantalum oxynitride.
[0089] In some embodiments, the metal oxynitride material is zirconium oxynitride.

[0090] In some embodiments, the metal oxynitride material comprises less than 50% oxygen.
[0091] In some embodiments, the metal oxynitride material comprises less than 50% nitrogen.
[0092] In some embodiments, the layer comprising the metal oxynitride material has a thickness of 1 nm to 20 nm.

[0093] In some embodiments, the thickness of the back contact is between 5 nm and 220 nm.
[0094] In some embodiments, the one or more layers containing zinc, cadmium, tellurium, or any combination thereof are: a first layer comprising the ternary cadmium, zinc, and tellurium; and a second layer comprising the binary of zinc and tellurium; the first layer of the one or more layers containing zinc, cadmium, tellurium, or any combination thereof comprising zinc, cadmium, tellurium or closer to the first surface of the back contact than a second layer of one or more layers containing any of these.

[0095] In some examples, the zinc and tellurium binaries are doped with copper, silver, or both.
[0096] In some embodiments, the back contact is disposed between a layer comprising a metal oxynitride material and one or more layers containing zinc, cadmium, tellurium, or any combination thereof. the high purity metal layer comprising at least 80% metal.

[0097] In one example, the metal of the high purity metal layer is titanium.
[0098] In some embodiments, the thickness of the high purity metal layer is less than the thickness of the layer comprising the metal oxynitride material.

[0099] In some embodiments, the back contact comprises a layer comprising a metal nitride material; located nearby; the metal nitride material has a concentration of metal between 30% and 70% and a concentration of nitrogen between 70% and 30%.

[00100] In some embodiments, the metal of the metal nitride material is molybdenum, titanium, tungsten, tantalum, or zirconium.
[00101] In some embodiments, the ratio of the thickness of the layer comprising the metal nitride material to the thickness of the layer comprising the metal oxynitride material is at least 2:1.

[00102] In some embodiments, the second surface of the back contact is formed by a layer comprising a metal nitride material.
[00103] In some embodiments, the back contact includes a second layer comprising a metal nitride material; the second layer comprising a metal nitride material is adjacent to the layer comprising a metal oxynitride material. .

[00104] In some embodiments, the back contact comprises a second layer comprising a metal oxynitride material; , zinc, cadmium, tellurium, or any combination thereof.

[00105] In some embodiments, the layer comprising the metal oxynitride material and the second layer comprising the metal oxynitride material are formed from different metal oxynitrides.
[00106] In some embodiments, the conductive layer is a second layer formed by a layer comprising chromium.
has a surface of

[00107] In some embodiments, the photovoltaic device includes an absorber layer comprising cadmium and tellurium, and the first surface of the back contact is adjacent to the absorber layer.
[00108] In another aspect, a photovoltaic device comprises an absorber layer comprising cadmium and tellurium; a back contact having a thickness defined between a first surface of the back contact contacting the absorbing layer, the back contact including a layer comprising a metal oxynitride material; one or more layers containing zinc, cadmium, tellurium, or any combination thereof located between the layers and the first surface of the back contact.

[00109] In some embodiments, the photovoltaic device includes a conductive layer having a surface formed by a layer comprising aluminum, and the second surface of the back contact contacts the surface of the conductive layer.

[00110] It should now be appreciated that embodiments of the present disclosure provide back contacts that include one or more layers of metal oxynitride. The back contacts provided herein exhibit low electrical resistivity, high work function, and thermal stability for high ohmic contacts. Correspondingly, the back contact described herein can form a low barrier contact to an absorber film comprising CdTe. Back contacts comprising one or more layers of metal oxynitride provided herein are substantially similar to the back contacts of photovoltaic devices, excluding one or more layers of metal oxynitride. were included in photovoltaic devices that demonstrated improved solar-electricity conversion efficiencies compared to photovoltaic devices of Higher efficiency was associated with improved photovoltaic device parameters (eg, higher short circuit current, higher fill factor, higher open circuit voltage, lower open circuit resistivity).

[00111] According to embodiments provided herein, a photovoltaic device can include a conductive layer and a back contact. The conductive layer may have a surface formed by a layer containing aluminum. The back contact may have a first surface, a second surface, and a thickness defined between the first surface of the back contact and the second surface of the back contact. A second surface of the back contact may contact the surface of the conductive layer. The back contact can include a layer including a metal oxynitride material and one or more layers including zinc, cadmium, tellurium, or any combination thereof. One or more layers comprising zinc, cadmium, tellurium, or any combination thereof may be located between the layer comprising the metal oxynitride material and the first surface of the back contact.

[00112] According to embodiments provided herein, a photovoltaic device can include an absorber layer and a back contact. Absorbent layers can include cadmium and tellurium. The back contact may have a first surface, a second surface, and a thickness defined between the first surface of the back contact and the second surface of the back contact. A first surface of the back contact may contact the absorbing layer. The back contact can include a layer including a metal oxynitride material and one or more layers including zinc, cadmium, tellurium, or any combination thereof. One or more layers comprising zinc, cadmium, tellurium, or any combination thereof may be located between the layer comprising the metal oxynitride material and the first surface of the back contact.

[00113] The terms "substantially" and "about" are used herein for any quantitative comparison,
It can be used to express an inherent degree of uncertainty that can be attributed to a value, measurement, or other expression. These terms are also utilized herein to denote the degree to which a quantitative expression can be varied from a stated baseline without changing the basic function of the subject matter in question.

[00114] While particular embodiments have been illustrated and described herein, it is appreciated that various other changes and modifications can be made without departing from the spirit and scope of the claimed subject matter. should understand. Furthermore, although various aspects of the claimed subject matter have been described herein, such aspects need not be utilized in combination. It is therefore intended that the appended claims cover all such changes and modifications that fall within the scope of the claimed subject matter.

Claims (52)

A photovoltaic device comprising a conductive layer having a surface formed by a layer comprising aluminum and a back contact,
the back contact has a first surface and a second surface and has a thickness defined between the first surface of the back contact and the second surface of the back contact;
a second surface of the back contact abuts a surface of the conductive layer, and the back contact:
a layer comprising a metal oxynitride material; and zinc, cadmium, tellurium, or any combination thereof located between the layer comprising the metal oxynitride material and the first surface of the back contact. comprising one or more layers that
photovoltaic device. 3. The photovoltaic device of Claim 1, wherein the metal oxynitride material comprises a Group IV transition metal, a Group V transition metal, or a Group VI transition metal. 3. The photovoltaic device of Claim 2, wherein the metal oxynitride material comprises less than about 70% Group IV transition metal, Group V transition metal, or Group VI transition metal. 4. The photovoltaic device of Claim 3, wherein said metal oxynitride material is titanium oxynitride. 4. The photovoltaic device of Claim 3, wherein said metal oxynitride material is tungsten oxynitride. 4. The photovoltaic device of Claim 3, wherein said metal oxynitride material is tantalum oxynitride. 4. The photovoltaic device of Claim 3, wherein said metal oxynitride material is zirconium oxynitride. 2. The photovoltaic device of Claim 1, wherein the metal oxynitride material contains less than 50% oxygen. 2. The photovoltaic device of Claim 1, wherein the metal oxynitride material comprises less than 50% nitrogen. 2. The photovoltaic device of claim 1, wherein the layer comprising metal oxynitride material has a thickness of 1 nm to 20 nm. The photovoltaic device of claim 1, wherein the back contact has a thickness of 5 nm to 220 nm. The one or more layers containing zinc, cadmium, tellurium, or any combination thereof comprises a first layer comprising the ternary components of cadmium, zinc, and tellurium and a binary component of zinc and tellurium. a second layer;
the first layer of the one or more layers containing zinc, cadmium, tellurium, or any combination thereof, wherein the first layer contains zinc, cadmium, tellurium, or any combination thereof; 2. The photovoltaic device of claim 1, wherein the back contact is located closer to the first surface of the back contact than the second layer of the plurality of layers. 13. The photovoltaic device of Claim 12, wherein the zinc and tellurium binaries are doped with copper, silver, or both. A layer of high purity metal wherein the back contact is disposed between the layer containing the metal oxynitride material and the layer or layers containing zinc, cadmium, tellurium, or any combination thereof. including
the high purity metal layer comprises at least 80% metal;
A photovoltaic device according to claim 1 . 15. The photovoltaic device of Claim 14, wherein the metal of said high purity metal layer is titanium. 15. The photovoltaic device of Claim 14, wherein the thickness of the high purity metal layer is less than the thickness of the layer comprising the metal oxynitride material. the back contact comprises a layer comprising a metal nitride material;
the layer comprising the metal nitride material is located closer to the second surface of the back contact than the layer comprising the metal oxynitride material;
wherein the metal nitride material has a metal concentration of 30% to 70% and a nitrogen concentration of 70% to 30%;
A photovoltaic device according to claim 1 . 18. The photovoltaic device of Claim 17, wherein the metal of said metal nitride material is molybdenum, titanium, tungsten, tantalum, or zirconium. 18. The photovoltaic device of Claim 17, wherein the ratio of the thickness of the layer comprising the metal nitride material to the thickness of the layer comprising the metal oxynitride material is at least 2:1. 18. The photovoltaic device of Claim 17, wherein a second surface of said back contact is formed by a layer comprising said metal nitride material. the back contact comprises a second layer comprising a metal nitride material;
wherein the second layer comprising the metal nitride material is adjacent to the layer comprising the metal oxynitride material;
18. The photovoltaic device of claim 17. the back contact comprises a second layer comprising a metal oxynitride material;
wherein the second layer comprising the metal oxynitride material comprises a layer comprising the metal oxynitride material and one or more layers comprising the zinc, cadmium, tellurium, or any combination thereof; located between
A photovoltaic device according to claim 1 . 23. The photovoltaic device of Claim 22, wherein the layer comprising the metal oxynitride material and the second layer comprising the metal oxynitride material are formed from different metal oxynitrides. 2. The photovoltaic device of Claim 1, wherein said conductive layer has a second surface formed by a layer comprising chromium. 2. The photovoltaic device of Claim 1, comprising an absorber layer comprising cadmium and tellurium, wherein the first surface of said back contact is adjacent said absorber layer. A photovoltaic device comprising an absorber layer comprising cadmium and tellurium and a back contact, wherein
the back contact has a first surface and a second surface and has a thickness defined between the back contact first surface and the back contact second surface;
a first surface of the back contact contacts the absorber layer, and the back contact:
a layer comprising a metal oxynitride material; and zinc, cadmium, tellurium, or any combination thereof located between the layer comprising the metal oxynitride material and the first surface of the back contact. comprising one or more layers that
photovoltaic device. 27. The photovoltaic device of Claim 26, comprising a conductive layer having a surface formed by a layer comprising aluminum, a second surface of said back contact contacting a surface of said conductive layer. 28. The photovoltaic device of any one of claims 1 and 26-27, wherein the metal oxynitride material comprises a Group IV transition metal, a Group V transition metal, or a Group VI transition metal. 29. The photovoltaic device of Claim 28, wherein the metal oxynitride material comprises less than about 70% Group IV transition metal, Group V transition metal, or Group VI transition metal. The photovoltaic device of any one of claims 1 and 26-29, wherein the metal oxynitride material is titanium oxynitride. The photovoltaic device of any one of claims 1 and 26-29, wherein the metal oxynitride material is tungsten oxynitride. The photovoltaic device of any one of claims 1 and 26-29, wherein the metal oxynitride material is tantalum oxynitride. The photovoltaic device of any one of claims 1 and 26-29, wherein said metal oxynitride material is zirconium oxynitride. 34. The photovoltaic device of any one of claims 1 and 26-33, wherein said metal oxynitride material comprises less than 50% oxygen. The photovoltaic device of any one of claims 1 and 26-34, wherein the metal oxynitride material comprises less than 50% nitrogen. The photovoltaic device of any one of claims 1 and 26-35, wherein the layer comprising the metal oxynitride material has a thickness of 1 nm to 20 nm. The photovoltaic device of any one of claims 1 and 26-36, wherein the thickness of the back contact is between 5 nm and 220 nm. The one or more layers containing zinc, cadmium, tellurium, or any combination thereof comprises a first layer comprising the ternary components of cadmium, zinc, and tellurium and a binary component of zinc and tellurium. a second layer;
the first layer of the one or more layers containing zinc, cadmium, tellurium, or any combination thereof, wherein the first layer contains zinc, cadmium, tellurium, or any combination thereof; or located closer to the first surface of the back contact than the second layer of the plurality of layers.
38. The photovoltaic device of any one of claims 1 and 26-37. 39. The photovoltaic device of Claim 38, wherein the zinc and tellurium binaries are doped with copper, silver, or both. wherein the back contact comprises a layer of high purity metal disposed between the layer containing the metal oxynitride material and the one or more layers containing zinc, cadmium, tellurium, or any combination thereof; including
the high purity metal layer comprises at least 80% metal;
40. The photovoltaic device of any one of claims 1 and 26-39. 41. The photovoltaic device of Claim 40, wherein the metal of said high purity metal layer is titanium. 42. The photovoltaic device of Claims 40 or 41, wherein the thickness of the high purity metal layer is less than the thickness of the layer comprising the metal oxynitride material. the back contact comprises a layer comprising a metal nitride material;
the layer comprising the metal nitride material is located closer to the second surface of the back contact than the layer comprising the metal oxynitride material;
wherein the metal nitride material has a metal concentration of 30% to 70% and a nitrogen concentration of 70% to 30%;
The photovoltaic device of any one of claims 1 and 26-42. 44. The photovoltaic device of Claim 43, wherein the metal of said metal nitride material is molybdenum, titanium, tungsten, tantalum, or zirconium. 45. The photovoltaic device of Claims 43 or 44, wherein the ratio of the thickness of the layer comprising the metal nitride material to the thickness of the layer comprising the metal oxynitride material is at least 2:1. 46. The photovoltaic device of any one of claims 43-45, wherein a second surface of said back contact is formed by a layer comprising said metal nitride material. the back contact comprises a second layer comprising a metal nitride material;
wherein the second layer comprising the metal nitride material is adjacent to the layer comprising the metal oxynitride material;
47. The photovoltaic device of Claim 46. the back contact comprises a second layer comprising a metal oxynitride material;
wherein the second layer comprising the metal oxynitride material comprises a layer comprising the metal oxynitride material and one or more layers comprising the zinc, cadmium, tellurium, or any combination thereof; located between
The photovoltaic device of any one of claims 33-47. 49. The photovoltaic device of Claim 48, wherein the layer comprising the metal oxynitride material and the second layer comprising the metal oxynitride material are formed from different metals. 50. The photovoltaic device of any one of claims 1 and 27-49, wherein said conductive layer has a second surface formed by a layer comprising chromium. 51. The photovoltaic device of any one of claims 1 and 28-50, comprising an absorber layer comprising cadmium and tellurium, wherein the first surface of the back contact is adjacent to the absorber layer. 52. The photovoltaic device of any one of claims 26-51, wherein the absorbing layer comprises selenium.

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